1. Field of the Invention
This invention relates to improvements in safety valves and more particularly, but not by way of limitation, to a safety valve for a pressure fluid flow line, and which may be utilized in combination with a punch tee, for automatically closing upon the sensing of pressure differentials thereacross for precluding accidental loss of the pressure fluid from the flow line.
2. Description of the Prior Art
It is frequently desirable to connect a main pressure fluid flow line with a secondary flow line in order to transport a portion of the pressure fluid to an auxiliary site. For example, in the fuel supply system of a city, such as the gas distribution system, it is frequently desirable to connect a new building or house to the gas distribution system in order to supply the new building with fuel. It is common practice to weld or otherwise secure a punch tee, or the like, to the outer periphery of the pipeline of the distribution system, and seal said fitting between the pipeline and an auxiliary flow line which extends to the building to be newly supplied with the fluid or fuel. Subsequent to the setting of the punch tee, a punch member is utilized for cutting or puncturing the outer periphery of the pipe to provide communication between the main pipeline and the auxiliary flow line through the punch tee. There are certain disadvantages in the presently available punch tees, however, in that in the event of a break in the auxiliary line, the pressure in the auxiliary line may drop suddenly and tend to quickly withdraw substantially great quantities of the fluid from the main pipeline. It will be readily apparent that such a situation may be extremely hazardous, particularly in the event the main distribution system carries natural gas, or the like.